', t.
ii., p. 45 and 202-209.
When the vesicles of vapor have become condensed into clouds, having
definite outlines, the electric tension of the external surface will be
increased in proportion to the amount of electricity which passes over to it
from the separate vesicles of vapor.*
[footnote] *Gay-Lussac, in the 'Annales de Chimie et de Physique', t.
viii., p. 167. In consequence of the discordant views of Lame, Becquerel,
and Peltier, it is difficult to come to a conclusion regarding the cause of
the specific distribution of electricity in clouds, some of which have a
positive, and others a negative tension. The negative electricity of the
air, which near high water-falls is caused by a disintegration of the drops
of water -- a fact originally noticed by Tralles, and confirmed by myself in
various latitudes -- is very remarkable, and is sufficiently intense to
produce an appreciable effect on a delicate electrometer at a distance of
300 or 400 feet.
Slate-gray clouds are charged, according to Peltier's experiments at Paris,
with negative, and white, red, and orange-colored clouds with positive
electricity. Thunder clouds not only envelop the highest summits of the
chain of the Andes (I have myself seen the electric effect of lightning on
one of the rocky pinnacles which project upward of 15,000 feet above the
crater of the volcano of Toluca), but they have also been observed at a
vertical height of 26,650 feet over the low
p 337
lands in the temperate zone.
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